#include <stdio.h>
char c[16000000]; 
int main()
{
	FILE *in,*out;
	int a[200],i,j,k,n,nr=0;
	in=fopen("tije.in","r");
	out=fopen("tije.out","w");
	fscanf(in,"%d",&n);
/*	for (i=1;i<=n;i++)
		a[i]=0;*/
	for (i=n-1;i>=1;i--)
	{
		for (j=1;j<=i;j++)
			fprintf(out,"%d %d\n",1,n+1);
		for (k=2;k<=n+1;k++)
			for (j=1;j<=i;j++)
				fprintf(out,"%d %d\n",k,k-1);
	}
	/*for (i=1;i<=n;i++)
	{
		for (j=i+1;j<=n;j++)
		{
			fprintf(out,"%d %d\n",j,n+1);
			fprintf(out,"%d %d\n",i,j);
		}
		for (j=1;j<=n-i;j++)
			fprintf(out,"%d %d\n",n+1,i);
		for (j=i+1;j<=n;j++)
		{
			fprintf(out,"%d %d\n",1,n+1);
			fprintf(out,"%d %d\n",j,1);
			for (k=1;k<n;k++)
				fprintf(out,"%d %d\n",j,n+1);
			fprintf(out,"%d %d\n",1,j);
			for (k=1;k<n;k++)
				fprintf(out,"%d %d\n",n+1,j);
			fprintf(out,"%d %d\n",n+1,1);
		}
		
		for (j=i+1;j<=n;j++)
		{
			if (a[i]>=a[j])
			{
				for (k=1;k<=a[i];k++)
					fprintf(out,"%d %d\n",i,n+1);
				for (k=1;k<=a[j];k++)
					fprintf(out,"%d %d\n",j,i);
				fprintf(out,"%d %d\n",n+1,j);
				for (k=1;k<a[j];k++)
					fprintf(out,"%d %d\n",i,j);
				for (k=1;k<a[i];k++)
					fprintf(out,"%d %d\n",n+1,i);
			}
			else
			{
				for (k=1;k<=a[j];k++)
					fprintf(out,"%d %d\n",j,n+1);
				for (k=1;k<=a[i];k++)
					fprintf(out,"%d %d\n",i,j);
				fprintf(out,"%d %d\n",n+1,i);
				for (k=1;k<a[i];k++)
					fprintf(out,"%d %d\n",j,i);
				for (k=1;k<a[j];k++)
					fprintf(out,"%d %d\n",n+1,j);
			}
			a[i]--;
			a[j]--;
		
	}*/
	fclose(in);
	fclose(out);
	return 0;
}